Add C++ Turbo Module Event Emitter example (#44810)

Summary:
Pull Request resolved: #44810

Adds an example how to use the `EventEmitter` on a (C++) Turbo Module

## Changelog:

[General] [Added] - Add C++ Turbo Module Event Emitter example

Reviewed By: javache

Differential Revision: D57473949

fbshipit-source-id: 1a8d17fb83af4220ef12379e0102b5b2e233ed45

packages/rn-tester/NativeCxxModuleExample/NativeCxxModuleExample.cpp

@@ -166,7 +166,14 @@ std::optional<bool> NativeCxxModuleExample::getWithWithOptionalArgs(
 }
 
 void NativeCxxModuleExample::voidFunc(jsi::Runtime& rt) {
-  // Nothing to do
+  // Emit some events
+  emitOnPress();
+  emitOnClick<std::string>("value from callback on click!");
+  emitOnChange(ObjectStruct{1, "two", std::nullopt});
+  emitOnSubmit(std::vector{
+      ObjectStruct{1, "two", std::nullopt},
+      ObjectStruct{3, "four", std::nullopt},
+      ObjectStruct{5, "six", std::nullopt}});
 }
 
 void NativeCxxModuleExample::setMenu(jsi::Runtime& rt, MenuItem menuItem) {

packages/rn-tester/NativeCxxModuleExample/NativeCxxModuleExample.js

@@ -9,6 +9,7 @@
  */
 
 import type {TurboModule} from 'react-native/Libraries/TurboModule/RCTExport';
+import type {EventEmitter} from 'react-native/Libraries/Types/CodegenTypes';
 
 import {TurboModuleRegistry} from 'react-native';
 
@@ -76,6 +77,10 @@ export type CustomDeviceEvent = {
 };
 
 export interface Spec extends TurboModule {
+  +onPress: EventEmitter<void>;
+  +onClick: EventEmitter<string>;
+  +onChange: EventEmitter<ObjectStruct>;
+  +onSubmit: EventEmitter<ObjectStruct[]>;
   +getArray: (arg: Array<ObjectStruct | null>) => Array<ObjectStruct | null>;
   +getBool: (arg: boolean) => boolean;
   +getConstants: () => ConstantsStruct;

packages/rn-tester/js/examples/TurboModule/NativeCxxModuleExampleExample.js

@@ -9,6 +9,7 @@
  */
 
 import type {RootTag} from 'react-native/Libraries/ReactNative/RootTag';
+import type {EventSubscription} from 'react-native/Libraries/vendor/emitter/EventEmitter';
 
 import NativeCxxModuleExample, {
   EnumInt,
@@ -72,6 +73,7 @@ type ErrorExamples =
 
 class NativeCxxModuleExampleExample extends React.Component<{||}, State> {
   static contextType: React$Context<RootTag> = RootTagContext;
+  eventSubscriptions: EventSubscription[] = [];
 
   state: State = {
     testResults: {},
@@ -262,6 +264,34 @@ class NativeCxxModuleExampleExample extends React.Component<{||}, State> {
         'Cannot load this example because TurboModule is not configured.',
       );
     }
+    if (NativeCxxModuleExample) {
+      this.eventSubscriptions.push(
+        NativeCxxModuleExample.onPress.addListener(value =>
+          console.log('onPress: ()'),
+        ),
+      );
+      this.eventSubscriptions.push(
+        NativeCxxModuleExample.onClick.addListener(value =>
+          console.log(`onClick: (${value})`),
+        ),
+      );
+      this.eventSubscriptions.push(
+        NativeCxxModuleExample.onChange.addListener(value =>
+          console.log(`onChange: (${JSON.stringify(value)})`),
+        ),
+      );
+      this.eventSubscriptions.push(
+        NativeCxxModuleExample.onSubmit.addListener(value =>
+          console.log(`onSubmit: (${JSON.stringify(value)})`),
+        ),
+      );
+    }
+  }
+
+  componentWillUnmount() {
+    for (const subscription of this.eventSubscriptions) {
+      subscription.remove();
+    }
   }
 
   render(): React.Node {